There's plenty of talk on BC about the "Grot traps" but is anyone able to show some pictures as to where is being referred to?
Having not built my car, i'm not 100% au fait with the inner workings, so some pictures would be really handy!
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No pictures I'm afraid but the grot traps are the narrow gap between the sideskins and the footwells on both sides of the car. Dirt and debris gets inside and lodges there getting wet and holding moisture. The result is rot which shows as bubbling on the outside of the bodywork. I rebuilt my car and lathered waxoyl in the gap and then fitted RIF panels to stop any further dirt entering. Car is 23 years old and no sign of corrosion.
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And adding to Paul's description, although the footwells/boxes are riveted and sealed to the chassis, the outer skin is not, Unfortunately this enables grot to travel much further back than would be expected, only stopping when it gets to the vertical chassis tube level with the dash.
The grot will hold moisture, even if only from condensation, and is the reason why there's often corrosion at the bottom of the skin below the scuttle ends. Inject as much protection in there as it'll take!
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Thanks both, particularly Stu for the pictures.
How does one go about cleaning that out, and then re-filling it with protection?
Unfortunately the only way to gain access to the level I did is to remove the inner skin.
The first winter I owned the car I decided to renew most of the interior panels and add plenty of corrosion protection, I didn't strip it specifically to address the grot trap issue although I'm glad I did, the muck was surprisingly moist underneath but thankfully the chassis tubes were still sound. At the time it was only 8 years old.
I used Waxoyl to protect everything, if I was doing it again I'd use one of the Bilt Hamber cavity treatments, Waxoyl is old technology and has in many ways been superseded. It also leaks out through the rivets on hot days, maybe due to the amount I used!
Thanks Stu for posting those pictures. It really helps me to understand the issue. I'm going to purchase a large bottle of Bilt Hamber Dynax UC to get into all the space. I'm still trying to figure out though how to get in there. I'm hoping that a pump sprayer with a long lance might work, although the nozzle might just gunk up immediately with the wax. Or is the Dynax thin enough to ensure that doesn't happen? I'd be interested to hear if anyone's tried it.
The journey is the destination
When using waxoyl it's always better to do it on a warm day when the waxoyl is thin. When I used waxoyl I used their pressure lance and stood the waxoyl tin a bucket of hot water. It enabled it to flow into the nooks and crannies.
I think the Dynax wax is relatively non-viscous. If I had access to a pressure line I'd be doing it properly. Unfortunately I don't have access to a work space so was thinking of using something like this:
I'm just hoping the nozzle doesn't clog up.
Simon, you should be using Dynax S50 in those hidden cavities. It comes with a long injection lance too.
Idea is to coat and let it run out, so jack up the car at the front to ensure it runs down.
Olly Amos - 2008 Caterham Superlight Sigma 150
Hi Olly, thanks for the reply. As I understand it the side panels need to come out in the cockpit to seal those grot traps - is that correct? Or is there some way to get the liquid in there without full removal? For example, I'm wondering if a small hole can be drilled in the panels to get the injection lance in there before using a rubber grommet to seal it up again.
I was planing on using Dynax UC in the engine compartment as I wanted to use something less visible in that area.